1. Field of the Invention
The present invention relates to a battery pack and more particularly, to a mobile battery charging pack, which has DC3.7V, DC5.0V and USB interface power input/output functions.
2. Description of the Related Art
Dry battery has been developed for a long period. Different battery boxes may be used to hold different battery cells in different electric or electronic products such as electronic toys, mini radios, flashlights, etc. There is known a charging battery box adapted to hold a rechargeable battery, for example, a nickel cadmium battery and to convert AC power supply into DC power supply for charging the rechargeable battery. These conventional battery boxes commonly have the battery cells connected in series to provide one particular DC voltage. A battery box may hold two battery cells that are positioned in parallel. However, these two battery cells are electrically connected in series.
Further, when the power of the battery of a mobile electronic device such as a PDA or the like is used up and there is no external power supply available for charging the battery of the mobile electronic device, the mobile electronic device becomes unworkable. Taiwan Patent 103972 (equivalent to U.S. Pat. No. 5,537,022), which was issued to the present inventor, discloses a battery pack entitled “ENCLOSED BATTERY HOLDER”. This design of battery pack is practical for use to charge the battery of a mobile electronic device.
Further, USB (Universal Series Bus) interface has been intensively used in computer electronics nowadays. A USB connector allows DC power input as well as DC power output. However, the aforesaid Taiwan Patent 103972 (equivalent to U.S. Pat. No. 5,537,022) does not provide a USB connector for obtaining DC power supply from one USB port of a personal computer.